Ok.....you guys are probably getting sick of me, but I hope someone on here can answer this question for me. I have had problems with this machine for a while and have replaced all of the fuel line, crush washers,bled all air, replaced all strainers, made sure there was no leaking on the settling bowl,new lift pump and put a new fuel cap on it. Each of these things seemed to help, but quickly went back to the same problem, where it takes 15-20 seconds to start, or will not start at all. Once it is running, it runs well and strong. So, my question is this: Would a bad boost compensator cause this problem? Or one out of adjustment? I have been doing some research and it seems to me that if it is bad or out of adjustment; that it could limit the amount of fuel to the pump during start up. This would make sense to me considering that once it is running, it runs strong. By my thinking if the maximum off boost injection volume is too low, it will not allow enough fuel until it senses enough boost. Am I incorrect in this line of thinking? Any help would be greatly appreciated.
Not familiar with your machine or history with it. But are you she it's fuel not electrical?
pretty sure. shut off solenoid is working and fuel governor checks out ok. it was sucking air for a while, but seem to have fixed that problem.
If any more air, I am down to steel tube lines or fuel filter mount housing. Had some clogged lines, replaced them. fuel cap was not venting and creating neg pressure in tank, fixed that. other than the fuel cutoff solenoid and the throttle control motor, there is nothing more electrical that I can find. My thoughts at this point are something cracked and leaking air, or something prohibiting initial fuel for start up. If you know of something electrical I may have overlooked I would be interested in checking it out. I am not a pro on this machine, Kinda learning as I go. Thanks
hey daddytrav does the amount of time between starts affect how it starts ? if so i would adapt a way to manually preprime fuel system to determine if system is draining back.
pretty sure your problem is related either with cam-crank signal, or fuel pump wrong adjustment. We had the same prob with a 400-7. Dealer came like 20 times to figure it out, they changed a bunch of parts without success. It finaly ends that the fuel pressure pump can be miss aligned when installed, and the fuel injected is not at the right time, making hard start, intermitent. Don`t remember right but I think its something with taper alignement or something like that when you installed the fuel pump. The trouble was made directly from factory, and it tooks like 2 years before Komatsu figure it out. I think that there is a speed or timing sensor at the fuel gear pump, if the ECU don`t get the right corelation between cam-crank-fuel it will not injected at the right time. Make sure ECU is receiving both signals from sensor. The engine should be running with one sensor unplugged, even if its coding in dash... hope it helps
is it common rail fuel system if so I had a 360b volvo that would have to spin over for a while before it would fire ( an injector was leaking oil pressure )and had a 6.0 international that would not crank when hot because the o rings in the high pressure oil side of the common rail would leak and not build enough pressure to tell the injectors to fire
ok....I disconnected the small tube between the manifold and the boost compensator and had the operator crank. As he did I blew a small amount of air into the tube. The machine started instantly. Now I am trying to adjust the off boost fuel and cannot find the right tool for the job. I need a 14mm socket big enough to put a 10 mm socket inside of. I am not sure that a pass through socket will allow that. Could anyone tell me what you would call a socket like that? I need to undo the 14mm while not turning the 10 mm. Any help would be greatly appreciated
Ok. The verdict is in. I pulled the cover off of the top of the boost compensator and below it there is a 10mm lock nut with a hex adjusting screw. This adjusts the off boost fuel. I turned that screw one turn and tried it. The machine started about twice as fast. I turned it one more turn and the machine fires in less than one second. So that was deffinately the problem. The boost compensator was not allowing the rack to advance in the injection pump enough to allow enough fuel for start up. After a lot of replacing fuel lines and system parts, it all came down to turning one screw two turns. starts and runs like a champ.